The city Utrecht has many beautiful old churches. One of the lesser known gems is the St Willibrord Church. The St Willibrord is a catholic church, where the tridentine (or Latin) mass is still celebrated. It is also a beautifully decorated church, that you must visit if you have a chance.
The church welcomes visitors on Friday and Saturday afternoon. Admission is free, but donations are welcome. For a small fee you can book a guided tour.
The church is in the Minrebroeder street, a 15 minute walk from the train station. Or you can take a bus to the nearby Janskerk bus stop.